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Toxoplasmosis, an innocuous disease?
Journal of Infection (1984) 8, 67-69
CASE R E P O R T Toxoplasmosis,
an innocuous
disease ?
C. C. B a k e r , C. P . F a r t h i n g * a n d P . R a t n e s a r *
The Wellcome Foundation Ltd, Beckenham, Kent * Farnborough Hospital, Kent Accepted for publication 26 April 1983 Summary This case report should remind physicians that toxoplasmosis may cause serious illness in healthy adults. Difficulties in the differential diagnosis of the disease are discussed. Introduction
Toxoplasma gondi is widespread among man and animals. Infections in adults rarely cause symptoms, yet illness due to infection by the organism is probably more common than is generally supposed. 1 We report a case in which the organism caused life-threatening disease. Case report T h e patient was a 33-year-old man who worked as an animal technician in a research laboratory. Among the various organisms which he had been handling during the course of his occupation was a supposedly avirulent strain (RH) of T. gondii. He was admitted to hospital complaining of vomiting, throbbing headache, tiredness and lethargy, generalized aches and fever with rigors which had lasted for 2 weeks. His general practitioner had noted a high unremitting fever (4o °C) for 12 d a y s and had treated him symptomatically for glandular fever. T h e patient had been referred to the E N T Unit because of dysphagia and glandular enlargement. On admission he was toxic, dehydrated, with a pulse rate of IOO per minute and a temperature o f 4 I °C. Examination revealed marked enlargement of lymph glands in the neck, axillae and groin, enlarged spleen and liver with abnormal results of liver function tests as well as a macular rash over his trunk. Investigations showed an increased erythrocyte sedimentation rate (ESR), relative neutropenia with an increase of monocytes and of atypical mononuclear cells together with thrombocytopenia (platelets 27 x 109/1). Screening tests for infectious mononucleosis were at first positive but later became negative. Blood cultures and tests for syphilis, malaria and brucellosis were negative. Initially he was given intravenous fluids and oral antipyretics. Two days after admission an ophthalmologist examined his eyes and could find no evidence of toxoplasmosis. Because of the possibility of occupationally acquired disease, however, treatment with sulphadimidine and pyrimethamine was begun. oi63-4453/84/oioo67+o 3 $02.o0/0
© 1984 The British Society for the Study of Infection 3-2
68
C. C. B A K E R , C. P. F A R T H I N G
A N D P. R A T N E S A R
Table I Toxoplasma dye test results Date 3 February I98I 2o February I98I 27 February i98i
IU/ml
Titre
2ooo 2ooo 500
8ooo 4ooo 2000
Results of Toxoplasma dye tests shown in Table I supported a diagnosis of toxoplasmosis. T h e patient improved slowly and was discharged from hospital on the 25th day. He resumed work 6 weeks later. Discussion
Primary toxoplasmosis in an adult commonly presents in one of two forms; either as a febrile lymphadenitis resembling glandular fever or as non-febrile enlargement of lymph glands without symptoms. As well as infectious mononucleosis, toxoplasmosis and infection with cytomegalovirus should be considered in patients with fever and lymphadenopathy. Although tests assist in the diagnosis of infectious mononucleosis false positive results may arise when the patient has another infection with a high antibody titre. T h e diagnosis of toxoplasmosis usually depends on its clinical presentation and the results of serological tests. Most toxoplasma infections are inapparent, those which are recognised being usually mild. Involvement of the eye is not common. When present, choroidoretinitis is thought to be caused by recurrence of congenital infection. 2 It is not found in the so-called acquired form of the disease. T h e mainstay of diagnosis of toxoplasmosis is the dye test. In normal infants aged o-6 months antibody titres are similar to those of their mothers. From 6 months to IO years of age i - i o per cent of the population have 8 I U / m l (titre of 16) or more, the percentage rising steeply with age, so that I25 I U / m l (titre of 256) may be expected in i per cent of adults. A finding of 25o I U / m l (titre of 512) or greater, together with clinical signs, suggests active disease. Other tests may be used to demonstrate antibody but many of them have problems of sensitivity or specificity.~ It is unusual for the organism to cause serious illness. Fatal, generalised toxoplasmosis has been reported in laboratory workers handling highly virulent strains and in patients on immuno-suppressive therapy. 1 Although our patient's occupation was relevant to his illness the strain of toxoplasma (RH) with which he was working was thought to be avirulent. T h e RH strain, however, has caused significant illness in three separate laboratory acquired cases, the last being reported in I972. 4 In our patient the most likely route of infection was respiratory by inhalation of aerosol. Toxoplasma gondii is considered to be of low pathogenicity (Category C) but, since this incident, staff in our laboratory working with the organisms have been issued with 'Medical Contact Cards' as recommended for those working in clinical laboratories. °
Toxoplasmosis, an innocuous disease?
69
References 1. Christie AB. Infectious Diseases : Epidemiology and Clinical Practice, 3rd ed. Edinburgh: Churchill Livingstone, I98O: 92o-934. 2. Jones TC. Toxoplasmosis. In: Wyngaarden JB, Smith LH, eds. Textbook of Medicine, x6th ed. Philadelphia: WB Saunders, I982: 1739-1742. 3. Fleck DG, Kwantes W. The Laboratory Diagnosis of Toxoplasmosis. London: HMSO, I98o. (Public Health Laboratory Service Monograph Series No. I3.) 4. Field PR, Moyle GG, Parnell PM. The accidental infection of a laboratory worker with Toxoplasma gondii. Med J Aust I972; 2: 196--I98. 5. Department of Health and Social Security. Code of Practice for the Prevention of Infection in Clinical Laboratories and Post-Mortem Rooms. London: HMSO, I979. (The Howie Code.)
CASE R E P O R T Toxoplasmosis,
an innocuous
disease ?
C. C. B a k e r , C. P . F a r t h i n g * a n d P . R a t n e s a r *
The Wellcome Foundation Ltd, Beckenham, Kent * Farnborough Hospital, Kent Accepted for publication 26 April 1983 Summary This case report should remind physicians that toxoplasmosis may cause serious illness in healthy adults. Difficulties in the differential diagnosis of the disease are discussed. Introduction
Toxoplasma gondi is widespread among man and animals. Infections in adults rarely cause symptoms, yet illness due to infection by the organism is probably more common than is generally supposed. 1 We report a case in which the organism caused life-threatening disease. Case report T h e patient was a 33-year-old man who worked as an animal technician in a research laboratory. Among the various organisms which he had been handling during the course of his occupation was a supposedly avirulent strain (RH) of T. gondii. He was admitted to hospital complaining of vomiting, throbbing headache, tiredness and lethargy, generalized aches and fever with rigors which had lasted for 2 weeks. His general practitioner had noted a high unremitting fever (4o °C) for 12 d a y s and had treated him symptomatically for glandular fever. T h e patient had been referred to the E N T Unit because of dysphagia and glandular enlargement. On admission he was toxic, dehydrated, with a pulse rate of IOO per minute and a temperature o f 4 I °C. Examination revealed marked enlargement of lymph glands in the neck, axillae and groin, enlarged spleen and liver with abnormal results of liver function tests as well as a macular rash over his trunk. Investigations showed an increased erythrocyte sedimentation rate (ESR), relative neutropenia with an increase of monocytes and of atypical mononuclear cells together with thrombocytopenia (platelets 27 x 109/1). Screening tests for infectious mononucleosis were at first positive but later became negative. Blood cultures and tests for syphilis, malaria and brucellosis were negative. Initially he was given intravenous fluids and oral antipyretics. Two days after admission an ophthalmologist examined his eyes and could find no evidence of toxoplasmosis. Because of the possibility of occupationally acquired disease, however, treatment with sulphadimidine and pyrimethamine was begun. oi63-4453/84/oioo67+o 3 $02.o0/0
© 1984 The British Society for the Study of Infection 3-2
68
C. C. B A K E R , C. P. F A R T H I N G
A N D P. R A T N E S A R
Table I Toxoplasma dye test results Date 3 February I98I 2o February I98I 27 February i98i
IU/ml
Titre
2ooo 2ooo 500
8ooo 4ooo 2000
Results of Toxoplasma dye tests shown in Table I supported a diagnosis of toxoplasmosis. T h e patient improved slowly and was discharged from hospital on the 25th day. He resumed work 6 weeks later. Discussion
Primary toxoplasmosis in an adult commonly presents in one of two forms; either as a febrile lymphadenitis resembling glandular fever or as non-febrile enlargement of lymph glands without symptoms. As well as infectious mononucleosis, toxoplasmosis and infection with cytomegalovirus should be considered in patients with fever and lymphadenopathy. Although tests assist in the diagnosis of infectious mononucleosis false positive results may arise when the patient has another infection with a high antibody titre. T h e diagnosis of toxoplasmosis usually depends on its clinical presentation and the results of serological tests. Most toxoplasma infections are inapparent, those which are recognised being usually mild. Involvement of the eye is not common. When present, choroidoretinitis is thought to be caused by recurrence of congenital infection. 2 It is not found in the so-called acquired form of the disease. T h e mainstay of diagnosis of toxoplasmosis is the dye test. In normal infants aged o-6 months antibody titres are similar to those of their mothers. From 6 months to IO years of age i - i o per cent of the population have 8 I U / m l (titre of 16) or more, the percentage rising steeply with age, so that I25 I U / m l (titre of 256) may be expected in i per cent of adults. A finding of 25o I U / m l (titre of 512) or greater, together with clinical signs, suggests active disease. Other tests may be used to demonstrate antibody but many of them have problems of sensitivity or specificity.~ It is unusual for the organism to cause serious illness. Fatal, generalised toxoplasmosis has been reported in laboratory workers handling highly virulent strains and in patients on immuno-suppressive therapy. 1 Although our patient's occupation was relevant to his illness the strain of toxoplasma (RH) with which he was working was thought to be avirulent. T h e RH strain, however, has caused significant illness in three separate laboratory acquired cases, the last being reported in I972. 4 In our patient the most likely route of infection was respiratory by inhalation of aerosol. Toxoplasma gondii is considered to be of low pathogenicity (Category C) but, since this incident, staff in our laboratory working with the organisms have been issued with 'Medical Contact Cards' as recommended for those working in clinical laboratories. °
Toxoplasmosis, an innocuous disease?
69
References 1. Christie AB. Infectious Diseases : Epidemiology and Clinical Practice, 3rd ed. Edinburgh: Churchill Livingstone, I98O: 92o-934. 2. Jones TC. Toxoplasmosis. In: Wyngaarden JB, Smith LH, eds. Textbook of Medicine, x6th ed. Philadelphia: WB Saunders, I982: 1739-1742. 3. Fleck DG, Kwantes W. The Laboratory Diagnosis of Toxoplasmosis. London: HMSO, I98o. (Public Health Laboratory Service Monograph Series No. I3.) 4. Field PR, Moyle GG, Parnell PM. The accidental infection of a laboratory worker with Toxoplasma gondii. Med J Aust I972; 2: 196--I98. 5. Department of Health and Social Security. Code of Practice for the Prevention of Infection in Clinical Laboratories and Post-Mortem Rooms. London: HMSO, I979. (The Howie Code.)